Risk Factors for the Adverse Events after Conversion from Twice-Daily to Once-Daily Tacrolimus in Stable Liver Transplantation Patients

Despite the therapeutic equivalence between twice-daily and once-daily tacrolimus, patient safety after conversion is still a concern. We reviewed 218 liver transplantation (LT) patients who converted twice-daily to once-daily tacrolimus between May 2011 and January 2014. Thirty (13.8%) patients had adverse events after conversion, with a liver function test (LFT) abnormality being the most common adverse event (n = 17). Despite the decrease in serum tacrolimus of > 30% after conversion, none of the patients who were converted to a dosage ratio (once-daily tacrolimus dosage: twice-daily tacrolimus dosage) > 1 had an LFT abnormality. Most patients with an LFT abnormality improved after increasing the once-daily tacrolimus dosage (n = 2), returned to a previous medication, and/or added another immunosuppressant (n = 15). One patient had acute cellular rejection, which improved after steroid pulse treatment, and another patient had graft failure. In patients with a dosage ratio ≤ 1, the conversion time within 5 years after LT was the only significant risk factor for an LFT abnormality after conversion (odds ratio: 11.850, 95% confidence interval: 1.321-106.325, P = 0.027). In conclusion, the dosage ratio and time after LT should be carefully considered during conversion from twice-daily to once-daily tacrolimus.